LA accessories on a Mag

[Scoots]

Hello all, its been a while for me. I am finally going to drop a Mag 5.2 in a lil Dak to go play at the drag strip. I know this is an E body forum but I figured out of all of the forums I am a member of, the best chance of finding a member who has performed this would be here.

I want to stay with V belt so I dont have to adapt a different PS pump and I can keep the factory AC compressor.

Please advise. Thx!

 

[Chryco Psycho]

I have not done this swap but Holley just released a bolt in kit for a gen 3 Hemi if that interests you ?

 

[rklein71]

Here is my 5.9 magnum, now a 408. I have EQ heads set up for a LA intake and used LA M/T valve covers. All LA stuff bolted on, although I did fab up brackets for a Sanden style AC compressor. This is in my 71 BHG.

 

[NoCar340]

I'm not 100% sure on this, since I don't mess with Magnums, but I think it's no more difficult than using the LA timing cover, and of course its attendant brackets. I don't think the bolt bosses on the ends of the heads changed. Is this an early Dakota? You say you don't want to change AC compressors, but the '90 from which I pulled a complete accessory drive was a serpentine arrangement--sorta half-LA, half-Magnum.

Your easiest course of action, of course, would be to find an '87-'89 Dakota with a 3.9 V6. It's literally a 318 with two cylinders lopped off, meaning pre-Magnum it's just a shorty LA. It should be a one-stop solution.

 

[moparleo]

If you change from the factory Magnum timing cover to the earlier LA cover you will have a couple of problems to fix. #1 is there is no fuel pump eccentric in the magnum cam as it was EFI and used an intank electric fuel pump. There is a cam snout adapter available to fix this. the timing mark will be in a different place with the different cover. The Magnum belt setup is much superior to the early v-belt set-up.
A later A/c compressor would be an up grade to the earlier ones. You are going one step forward with the Magnum engine and 2 steps back trying to use the old accessories. If you have the complete Magnum assembly, there is really no money to upgrade everything as you already have the parts.
Diy - Magnum Swap!!

 

[NoCar340]

The position of the timing marks relative to crankshaft position did not change between LA and Magnum balancers. An '89 318LA and '92 5.2L Magnum use the same balancer. Small-block timing marks never changed position after 1970.
Being that we're talking about a drag vehicle, the fuel pump eccentric "issue" would probably be skirted completely with an electric pump. If not, use an LA camshaft. It's not like hydraulic roller cams are rare, and I'd expect a cam swap is part of the plan already for a strip toy.
There is no later Magnum AC pump that is measurably better than what's already on an early Dakota with V-belts. They're both axial compressors. The major functional difference is the clutch itself, because of the different belt style. There's no good reason to open the system if it's not already.

 

[Scoots]

Thanks for all the info folks. No Hemi for me, just too expensive to swap. This is a very basic budget build with 90% of what I have laying around. This is a 90 3.9 Dak and yes I'll be disabling the EFI pump and using a commercial Stewart Warner electric so no issues there. No cam swap at first. The only things I'm doing is pulling the deads to have checked for the infamous cracks, hand lapping the valves, maybe a valve job depending on $. Then I'm installing .30 or.27 head gaskets to bump the compression a bit. I am also putting on a Seedmaster Eddy knock-off dual plane. I have 12 Mopar hp valve springs but dont know if I want to buy the rest, retainers and keepers just yet, probably wait till I go with a cam.

So heres what Ive been told but havent verified.. not all LA accessories have mounting holes on a Mag? There is a water pump with a shorter snout that needs to be used due to the radiator being so close and if so, what pump?

On another note, I do like the Mag serp setup but have been told a 92+ ps pump doesent use the same line/fitting as 91-? I actually would love to stay serp and would almost ditch the AC because I do have a Mag Paxton blower sitting. Ive heard its a pain to get a carb right with a centrifugal blower but boy that be cool!